The invention relates to a luminaire body for a medical light, especially a surgery light, with at least two electric bulbs a first of which in normal operation is disposed with its bulb socket in a given centered position in the stationary part of the luminaire body, while a second bulb with its bulb socket is in a reserve position outside of the centered position, and in case of failure of the first bulb the sockets of both bulbs are variable in their position by an electromagnetically operated turning system, so that the second bulb can be turned into the centered position for reserve bulb operation after the first bulb is withdrawn from the centered position; the invention is furthermore addressed to the use of such a luminaire body.
A lighting device having two electric bulbs operated alternately, such as disclosed, for example, in DE 200 04 384 U1, is known as a luminaire body; such a luminaire body is situated in the center or focal point of a reflector surrounding it, preferably an annular reflector, the reflector and luminaire body forming a common unit as a medical light or surgery light, which is mounted for rotation and turning by means of a hanger.
In U.S. Pat. No. 5,032,962 a surgery light is disclosed, which has a lighting device with two alternately energized bulbs of the same type, one of which is in a centered position optimized with respect to one reflector of the lighting device, while a second bulb remains in a reserve position in the case of normal operation. Upon the occurrence of a defect in the bulb in a first bulb socket, the first bulb is removed from the focal point of the reflector by means of a turning system and the second lamp that has previously served as a reserve bulb is positioned at the focal point.
In this manner, in case of failure of the first bulb, a virtually interruption-free lighting of the surgical field is to be made possible by a momentary switch-over to the reserve bulb while the optimal setting of the centered position in the focal point of the reflector is also retained.
If now however two discharge lamps are used as the main bulb and reserve bulb, the fail-safe quality may also be impaired by problems in the comparatively complex power supply to the gas discharge bulbs. This means that, to improve fail-safety, either a redundancy is to be provided in the power supply to the gas discharge bulbs, or in the event of failure of a single power supply to gas discharge lamps, the reserve function of the second lamp is no longer able to operate.
Furthermore, EP 0 730 120 A1 and corresponding DE 195 07 306 disclose a surgery lighting device which has at least one main bulb arranged at a required location and a replacement bulb in a waiting location close to this required location. The main bulb and the replacement bulb are adjustably mounted and controlled such that, if the main bulb burns out it is moved away from the required location and the replacement bulb is moved from the waiting location to the required location and there it is locked. The main bulb and the replacement bulb are mounted on sockets that can be moved independently of one another.
What is involved is two incandescent lamps of equal value which are supplied alternately by a common power source. Consequently an improvement of safety against failure is possible only by adding an additional power supply, which could be expected to result in an increase in cost.
Furthermore, DE 299 21 180 U1 has disclosed a fail-safe lighting device, especially one for surgical systems, which contains at least one gas discharge light bulb, the bulb having a supply unit which is connected to an additional safety power supply by switching over to a substitute power source in case of trouble. The power supply unit has a buffer storage which, upon the occurrence of trouble, provides a supply of energy for the operation of the gas discharge bulb during the changeover to the substitute power source.
The invention is addressed to the problem of creating a surgery lighting device with a main bulb and a reserve bulb, in which one of the two bulbs is configured as a discharge light bulb, while the reserve bulb is one which in its design or power is not simply equivalent to the gas discharge bulb. At the same time an optimal centered position in the reflector area is to be assumed by the reserve bulb in the case of reserve bulb operation.
The problem is solved by the invention in that the first bulb is configured as a double-ended gas discharge bulb with its contacts at its axially opposite ends, which is held and contacted in a first socket at one end, together with a second lamp configured as an incandescent bulb, which together with a second socket arranged at a distance for holding and contacting the other end of the gas discharge bulb as part of a turning device which can rotate about an axis, while by a releasing action a rotation of the turning device can be produced by means of a biased torsion spring between the turning device and the stationary part of the luminaire body.
It proves to be especially advantageous that, due to its construction, after a bulb failure a restoration of the main light (first bulb) is always necessary for the bulb change, so that after replacement of the defective main bulb it is always assured that the first lamp or discharge lamp is in the optimal position of the illumination system for normal operation.
Advantageous embodiments of the luminaire body and method of using the luminiare are described herein.
Preferably the rotation of the turning device is started by an electromagnetic release of a locking pin which is positively engaged in one of the bulb sockets, which is connected mechanically and electrically to the stationary part of the luminaire body.
The torsion spring needed in order to perform the swiveling action engages a point on the turning device off-center from the axis of rotation of the turning device.
In a preferred embodiment, one of the two bulb sockets is provided with at least one bore for positive engagement by the snapping-in of the locking pin, the latter being subjected to mechanical bias by a spring biased against the direction of the raising of the locking device.
Advantageously, the locking pin is completely removed from the bore in the bulb socket when the locking device is magnetically excited.
Furthermore, in the area of the bore provided for the locking pin, the bulb socket has a ramp surface to enable the locking pin to slide thereon until it enters into the opening.
For the repositioning of the first bulb into the centered position after bulb failure, a rotation of the turning device against the force of the torsion spring is required, this turning movement being advantageously performed manually.
The connecting contacts at the opposite ends of the gas discharge bulb operated as the first bulb are disposed along an axis that runs parallel to the axis of the turning device.
In an advantageous application, the luminaire body is inserted into an annular light which has an annular reflector spaced away from the luminaire body, so that optimum removal of the radiant heat can be performed by natural convection.
The subject matter of the invention is further explained below with the aid of FIGS. 1 to 3.